TERM 1
why doubly reinforce?
DEFINITION 1
1) reduce long term deflections due to creep- compression
steel retards creep along with tension steel2) increased
ductility and likelihood of tension controlled failure (good
behavior)3) ease of fabrication (holds up stirrups)4) limited
beam depth5) locations which experience both positive and
negative moments
TERM 2
Increased ductility does what for doubly
reinforced beams
DEFINITION 2
1) compression steel carries some of the compressive load,
therefore need less concrete to carry remaining load- stress
block is not as deep- NA moves higher in cross section- more
strain in tension steel- more elongation in the steel- more
ductility in cross section
TERM 3
double reinforcement increases moment
compactity by what?
DEFINITION 3
approx. 5 %
TERM 4
cracks
DEFINITION 4
- flexural cracks are vertical- shear cracks are diagonal at
approx. 45 deg.
TERM 5
inclined cracking in reinforced concrete
beams
DEFINITION 5
- shear cracks may start out as bond cracks and develope
into shear cracks- flexural -shear cracks- starts out as a
flexural crack and propagates due to shear stress- all
stresses are related (use mohr's circle)
